NURBS曲线S形加减速寻回实时插补算法  

The Real-time Algorithm of NURBS Curve Retriever Interpolation with S-type Acceleration and Deceleration Control

作　　者：刘献礼[1] 周肖阳 李茂月[1] 丁云鹏[1] 丁文彬[1] 

机构地区：[1]哈尔滨理工大学机械动力工程学院,哈尔滨150080

出　　处：《机械工程学报》2017年第3期183-192,共10页Journal of Mechanical Engineering

基　　金：国家自然科学基金重点资助项目(51235003)

摘　　要：针对高速高精加工中传统的NURBS算法沿曲线方向进行单一插补时,曲线的弧长与参数之间无精确的解析关系、进给速度又总是受到非线性变化的曲线曲率约束,导致基于S型加减速进行NURBS插补时,曲线长度的实时计算以及对减速点的预测十分困难,无法获得曲线余下部分的速度约束信息,而且在进行实时插补的过程中可能出现计算负荷过大、导致数据饥饿的现象,影响整个系统的实时性。针对以上问题,提出了一种寻回插补实时算法。该算法不依赖于曲线弧长的精确计算,采用正向与反向同步插补的方法。在前瞻插补模块中先对曲线进行逆向插补,确定正反向插补的校验点,以及正向插补所需的相关信息;在实时插补模块中,通过对比校验点的速度,判断是调用逆向插补的数据还是继续进行正向插补,从而实现满足速度约束条件的最优插补。该算法无须求解高次方程并可以保证以确定的速度通过曲率极值点和曲线终点,很好地保证了插补过程中的实时性。通过插补实例证明了算法简单高效、适应性以及实时性好,能够满足高速高精度数控加工的要求。During the high-speed precision machining processes with traditional curve interpolation in single direction,there is no accurate analytical relationship between the curve and the parameter.Furthermore,the feed rate is always restricted by the non-linearly varying curvature and the real-time calculation of the curve length and the prediction of the deceleration point can be difficult.More importantly,the traditional curve interpolation cannot get the rest of speed constraint information and it also can increase the amount of calculation which appears data starvation,then affects the entire real-time system.To solve the above problem,the algorithm of NURBS curve retriever interpolation is proposed.The algorithm applies the forward and reverse asynchronous interpolation method which do not rely on the precise calculation of arc length.The proposed algorithm determines the checkpoint and the relevant information of forward and reverse interpolation in the look ahead interpolation module.In the real-time module,the proposed algorithm determines whether to call the reverse interpolation data or proceed to interpolate by comparing the speed of the checkpoint in order to obtain the optimal interpolation which obey the speed restrictions.At last,the interpolation test not only prove the simplicity,efficiency and adaptability of the algorithm but also the ability to meet the requirements of both high speed and high accuracy of computer numerical control.

关 键 词：NURBS运动控制 实时插补 高速加工 S型加减速 

分 类 号：TP273[自动化与计算机技术—检测技术与自动化装置]